Fuze for a gyratory projectile



Jan. 21,1964 J. R. JASSE FUZE FOR A GYRATORY PROJECTILE 2 Sheets-Sheet 1 Filed Nov. 10, 1961 Jan. 21, 1964 J, JASSE 3,118,379

' FUZE FOR A GYRATORY PROJECTILE Filed NOV. 10, 1961 2 Sheets-Sheet 2 United States Patent 3,118,379 FUZE FUR A GYRATQRY PRQJECTILE Joseph Raymond .lasse, Paris, France, assignor to Hutchlnss-lhrandt, llaris, France, a French body corporate Filed Nov. 1t 1961, Ser. No. 151,578 Claims priority, application France Nov. 23, 1960 14 Claims. (Cl. 162-79) The present invention relates to fuzes for gyratory projectiles.

A type of fuze is known in which a device which affects a portion of the pyrotechnic chain or train is movable between a retracted position in which the pyrotechnic chain is broken by the device and an operative position which the device automatically assumes during the gyration of the projectile and in which the pyrotechnic chain is re established.

The object of the invention is to provide a fuze of this type so improved as to afford, in addition to complete safety at rest afforded by the breaking of the pyrotechnic chain, safety in the vicinity of the muzzle of the gun or launching tube. This result is obtained owing to the fact that the movable device is a detonator carrier disposed in a strictly fluidtight compartment where it forms two chambers which communicate only by Way of narrow passageways formed around said device and which are substan tially filled with a liquid having a retarding action.

Further features and advantages of the invention will be apparent from the ensuing description, with reference to the accompanying drawings to which the invention is in no way limited.

In the drawings:

FIG. 1 is a part-longitudinal sectional view and partelevational view of an automatically destroyed and percussion fuze for a gyratory projectile improved in accordance with the invention, this fuze being shown in its position of rest;

FIG. 2 is a half longitudinal sectional view similar to FIG. 1, the component parts being shown in their posi tions subsequent to arming;

FIG. 3 is a plan view taken along line 33 of FIG. 1 of the rear part of the fuze, and

FIG. 4 is a similar plan view relating to the positions shown in FIG. 2.

in the drawing, the invention is shown to be applied to a percussion and automatically destroyed fuze of the type described in the French addition No. 43,453 of February 18, 1933.

This fuze has an outer body having a longitudinal axis X-X and comprising three parts: a nose 1, an intermediate part 2 and a rear part 3 which are interconnected by screwthreads 4 and 5. The rear element 3: is screwthreaded at 6 for its screwthreaded mounting on the projectile P.

The three parts or elements It, 2 and 3 have an axial throughway aperture.

The part 1 has a stepped aperture comprising three cylindrical portions whose cross-sectional sizes increase from the forward portion '7 to the rear portion 9 and are interconnected by intermediate conical portions, a shoulder 13 being formed at the rear end of the portion 7.

The intermediate part or element 2 has a fiat rear transverse face 15 and a forward recess including a forward conical seating 16 which converges rearwardly toward the axis and is extended by a cylindrical axial aperture 17 provided with a neck 18 and communicating with the rear face 15.

The rear part or element 3 comprises a forward recess of revolution about the axis X-X, this recess consisting of a forward screwthreaded portion for interconnecting the parts 2. and 3 and a cylindrical rear portion 19 having a smooth wml. The portion 119 communicates by way "ice of an axial aperture Ztl with a rear cavity 21 of a cylindrical and hollow depending portion 21 which is closed by a tapped plug 21 Located in the axial cavity formed by the nose 1 is a percussion device A with its means for locking the firing pin at rest, and means for arming and actuating the firing pin for the automatic destruction.

The compartment formed by the cylindrical recess 19 and the rear face 15 of the intermediate part 2 of the body of the fuze contains the detonator carrier or arming element B described hereinafter and movable between a retracted position (H68. 1 and 3) and an operative or arming position (FIGS. 2 and 4) which correspond respectively to the breaking and to the re-establishment of the pyrotechnic chain or train, the detonator primer C (FIG. 2) having a charge 0 being adapted to be fired by the device A in the operative position of the detonator carrier B (FIGS. 2 and 4).

The rear part 3 carries in the aperture 20 a detonation relay D having a charge d adapted to be ignited when the detonator primer C has been fired and in the cavity 21 a booster E whose charge e is adapted to be ignited by the charge d.

Each of the devices A and B will now be described.

The percussion or firing device A comprises an axial percussion or firing pin consisting of two parts 22 and 2,3, the rear part 23 being disposed with clearance in a blind hole in the forward part 22. The latter is guided in the cylindrical portion '7 of the axial aperture of the nose 1 and is retained in the body of the fuze by a sealing disc 25 fixed by crimping over the end of the nose 1 onto a Washer 25 The rear part 23 of the firing pin terminates in the percussion point 26 and comprises a flange 27 whose rear face 28 is conical whereas its forward face constitutes a transverse shoulder 29 perpendicular to the axis XX.

T re firing pin is provided with the following devices.

Firstly, a combined device which effects the locking f the firing pin in the position of rest shown in FIG. 1, so that the point 26 is held in retracted position within the aperture 17 where it is guided by the neck portion 18, and the arming.

Secondly, a device for effecting the automatic destruction of the fuze after a given travel of the projectile if the fuze does not encounter the target beforehand.

The first of said devices comprises an arming sleeve 3% axially guided in the nose 1 by the faces 8 and 9, locking balls 31 adapted to co-operate with the sleeve 30 and with the firm pin, and an elastic split ring 32 engaged in an outer groove in the sleeve for holding the latter in the position of rest shown in P16. 1 by the forward abutment thereof against the rear face 3% of the nose 1. The arming sleeve 30 has a plurality of cylindrical recesses or countersinks 33, one recess being provided for each ball 31. These recesses are inclined relative to the axis of the fuze. The surface of each of the recesses is such that for the rear position of rest of the sleeve 30, the balls 31 of the intermediate part 2 and with the rear conical face 28 of the flange of the firing pin so that the latter is maintained in its forward position of rest shown in FIG. 1.

The device for effecting an automatic destruction of the fuze comprises an automatic destruction ring 34 slidable along the firing pin and urged rearwardly by an automatic destruction spring 35 which is compressed between the forward shoulder 13 of the nose 1 and a shoulder 36 on the ring 34. The latter has radial apertures 37 in each of which is partially engaged a ball 38. The balls 38 are capable of partially engaging a recess 39 formed in the inner face of the arming sleeve 3%. Therefore, they hold the ring 34 stationary relative to the sleeve 34) in the longitudinal direction at least while they are engaged in the apertures 39, since, as will be explained hereinafter,

at the moment of autoinahc destruction the balls retract in the direction toward the axis XX into the apertures 37 of the ring 34 so as to release the latter.

The detonator carrier or arming element B provided with the detonator primer C is, as has been mentioned hereinbefore, located in the cylindrical recess or compartment 19 formed in the rear part 3 of the body of the fuze and closed at the forward end by the rear face 15 of the intermediate part 2. The central aperture 13 of the intermediate part is closed by a thin fluid-tight disc 40 secured in the rear end of this aperture.

Further, machined across the screwthreading of the part 2., provided for the screwthreaded engagement of the latter with the part 3, are two longitudinal diametrically opposed fiat faces 46 The latter (FIG. 1) communicate with two radial cavities 4-13 formed in the part 2. Each of these cavities contains a compressible plug 463", for example of foam rubber.

As will be understood, the fiat faces 442* form two escape passageways while the part 2 has not been entirely screwed into the part 3 then, when the fiuidtightness between the two parts has been obtained by the contact at 40 of their perfectly machined mutual contact transverse faces, the compartment 19 is completely fiuidtight but communicates by way of the flat faces 4 h with the recesses 40 for the purpose explained hereinafter.

In the recess or compartment 19 the detonator carrier B is mounted for pivotal movement about the axis Y--Y of a pivot 41 which is eccentric relative to the longitudinal axis X-X (FIGS. 1 and 3) and can move from the retracted position of rest shown in FIGS. 1 and 3 to the operative position shown in FIGS. 2 and 4 in which the pyrotechnic chain or train is reestablished.

At rest, the detonator carrier B is held in the retracted position by a spring 42. This position is such that the detonator primer C is held away from the axis XX whereas it is returned to this axis in the operative position shown in FIGS. 2 and 4.

The arrangement is such that the centre of gravity of the detonator carrier B is located at a point G (FIG. 3) which is such that when the projectile revolves about its axis in the direction of arrow f the centrifugal force F exerted on the detonator carrier and applied at G creates relative to the pivot axis Y-Y of the detonator carrier a torque F a which tends to swing the detonator carrier about the axis YY in the direction of arrow F.

A suitable position of the centre of gravity G can be obtained in forming the detonator carrier B in two parts 43 and 44 having different densities.

By way of example, the part 33 can advantageously be composed of a light material, for example light alloy or a superpolyamide such as that known under the trade name Rilsan or any other plastic material whereas the other part 44 is composed of much heavier material, such as silver, brass or titanium carbide.

Dispose-d within the cavity 19, in addition to the detonator carrier B, are two fixed filling elements 47 and 47 held in position by studs 48 and 4d? The element 47 comprises a cylindrical face 5% which is concentric with the axis YY and in the immediate vicinity of which is located the cylindrical face 51 of the part 44 of the detonator carrier B.

The element 47 also comprises a cylindrical face 59* (FIG. 3) concentric to the axis YY and in the immediate vicinity of which is located the cylindrical face 51 of the detonator carrier B.

Thus, this detonator carrier forms, within the fluidtight compartment 19 in which it pivots, two chambers m and n which, on the one hand, communicate separately and permanently with one of the cavities 43 (PEG. 1) of the part 2 through one of the receses til and, on the other hand, communicate with one another only through very thin laminar flow passages respectively corresponding to the following clearances; 2:, formed between the faces 59 and 51 (FIGS. 1 and 3), x formed between the faces 5t and 51 y (FIG. 1) formed between the faces 15 and the face 52 of the detonator carrier B and z (nil in FIG. 1) formed between the bottom 53 of the recess 19 and the corresponding face 54 of the detonator carrier B.

The chambers in, n, the recesses 40 and the empty parts of the recesses 40* are completely filled with a liquid 55, preferably silicon. Before screwing the part 2 in the part 3 the cavity of the latter receives an amount of silicon which slightly exceeds the volume the cavity has after the parts 2 and 3 have been assembled. In the course of screwing, the excess silicon is evacuated by way of the flat faces or recesses 4th. The two compressible plugs 4% permit avoiding excessive overpressures of the silicon due to the difference in the expansion of this liquid and the metal elements defining the various walls of the compartment filled with the silicon.

The fuze operates in the following manner:

At rest, the various parts are in the positions shown in FIGS. 1 and 3, the firing pin is held stationary by the balls 51, the arming sleeve 3t) being maintained in its rear posi tion by the elastically yieldable ring 33. Further, the automatic destruction ring 3-4 bears against the forward face 29 of the flange 27 of the firing pin under the effect of the spring 35 which is compressed in the position shown in FIG. 1. The detonator carrier B is in the position shown in FIG. 3, the detonator primer C is laterally retracted away from the axis X-X along which the pyrotechnic chain is to be established.

The fuze is now completely safe for storing, handling and loading.

Upon firing the projectile from the gun tube, the ring 32 escapes from the groove of the arming sleeve 39 under the combined effect of uial acceleration and centrifugal acceleration, but, during the entire period of positive axial acceleration, that is, not only so long as the projectile travels through the gun tube but even over a certain distance after issuing from the tube, the balls 31 are urged by the positive axial acceleration against the rear seating 16 and everything remains temporarily in the same condition.

But, as soon as the positive axial acceleration ceases and under the effect of centrifugal force, these balls 31 in bearing against the faces 33 of the sleeve 30, axially shift this sleeve forwardly by a wedging action between the faces to and 33. The sleeve 3% then passes from the position shown in FIG. 1 to the armed position shown in FIG. 2.

Meanwhile, owing to the centrifugal force the balls 38 engaged in the apertures 37 of the automatic destruction ring 34 engage, as soon as the projectile is launched, the recesses 39 of the arming sleeve 30 so that the latter, in the course of its forward displacement, entrains therewith the automatic destruction ring 34 (compare the positions shown in FIGS. 1 and 2) and the spring 35- is highly compressed.

Further, during the entire period of positive acceleration the latter urges the rear face of the detonator carrier B against the end of the cavity 19 and prevents the detonator carrier from being pivoted in the direction of arrow 7' by the effect of the centrifugal force. This pivotal move prevented by the fact that as the directhe fuze about the axis XX (the arrows f and f shown in FIG. 3 have the same direction) upon launching the projectile the angular acceleration of the fuze maintains by inertia the detonator carrier in the position of rest shown in FIGS. 1 technic chain is broken and the part 43 of the detonator carrier abuts the fixed element 47 There is therefore complete safety during the entire period corresponding to safe use in the vicinity of the muzzle of the gun tube. But, after the positive axial acceleration and the angular acceleration cease, under the effect of centrifugal force F the detonator carrier B finally pivots about the axis YY in the direction of arrow (FIG. 3) in opposition to the action of the Spring 42 and at a pivotal speed which is damped or retarded by the silicon which must flow through the clearances x x y and z from the chamber n to the chamber In. Therefore, the detonator carrier moves from the retracted position shown in FIGS. 1 and 3 to the operative position shown in F168. 2 and 4 in which the detonator primer C arrives on the axis X-X thereby establishing the pyrotechnic chain. This position, which is determined in a very precise manner by the abutment f the part 4-3 of the detonator carrier against the face 19 (FIG. 4), is such that the detonator primer C is located exactly in front of the relay D of the pyrotechnic chain and on the axis of the firing pin.

It will be understood that in suitably cho sing the aforementioned clearances and the viscosity of the silicon, it is possible to regulate the time that the detonator carrier takes to reach the position shown in FIGS. 2 and 4 in which it permits percussion or firing and consequently the transmission or" the flame of the detonator primer C to the relay D.

in so choosing these values, it is therefore possible to regulate the period of safety afforded by the fuze in the vicinity of the gun tube muzzle after the projectile leaves the latter.

When the various parts have moved in the manner described hereinbelore, the fuze is armed, since: firstly the firing pin is unlocked; secondly the automatic destruction device constituted by the ring 34 and the spring 35 isitself armed since the ring 34- is separated from the shoulder 29 of the firing pin 23 an axial distance w (FIG. 2) which is substantiajy equal to the axial arming travel of the ring 30 and the spring 35 is compressed; and thirdly the pyrotechnic chain or train is established as explained hereinbefore.

The armed fuze can operate either by percussion upon impact on the target aimed at or by an automatic percussion following a slowing down of the rotational speed of the projectile on its trajectory, which slowing down is caused by the friction of the air.

in the case of percussion on the target, the latter crushes the nose of the fuze and the firing pin (which is released from the balls 31 and 38) is shifted rearwardly, perforates the disc 40 and strikes the detonator primer C which ignites the relay D which latter in turn ignites the booster E.

On the other hand, in the event of slowing down due to the friction of the air the projectile not having encountered the target, the effect of the centrifugal force exerted on the balls 33 becomes less than the effect of the spring 35 and the latter throws the ring 34 rearwardly against the flange of the firing pin 23, the point 26 of Which pierces the sealing disc 40 and strikes the detonator primer C.

The fuze is simple in construction and completely safe in operation, since the presence of silicon in the cavity 19 and the choice of its viscosity and of the clearance x x y and z permits obtaining delays in the arming which can be varied between some hundredths and some tenths of a second.

Although a specific embodiment of the invention has een described, many modifications and changes may be made therein without departing from the scope of the invention as defined in the appended claims.

Having now described my invention what I claim as new and desire to secure by Letters Patent is:

1. Fuze for a gyratory projectile having a bursting charge, said fuze comprising a body and within the body: a pyrotechnic chain for igniting the bursting charge of the projectile and including a detonator primer, a wall defining a fiuidtight compartment within the body, a detonator carrier disposed in the compartment and carrying the detonator primer and movable in the compartment between an operative position m which the detonator primer of the pyrotechnic chain communicates with so as to be capable of igniting the rest of the pyrotechnic chain and a retracted position in which the detonator primer does not communicate with the rest of the pyrotechnic chain, yieldable retaining means in engagement with the detonator carrier to yieldingly retain the detonator carrier in said retracted position when the projectile is not gyrating, the detonator carrier and retaining means being so adapted and arranged that the effect thereon of the gymtion of the projectile is to move the detonator carrier from said retracted position in opposition to the action of the retaining means to said operat've position, and the detonator carrier dividing the compartment into two chambers, small-section passageways provided between the detonator carrier and said wall defining the compartment and putting the chambers in communication with each other, and a motion damping liquid filling the chambers and passageways whereby the movement of the detonator carrier from the retracted position to the operative position is retarded by the action of the liquid which is constrained to flow from one chamber to the other by way of said passageways.

2. Fuze as claimed in claim 1, comprising elastically compressible means the volume of which varies with pressure change disposed within the body in communication with the compartment whereby relative variations in the volume of the liquid and the volume of the chambers due to difierences in expansion of the liquid and of the detonator carrier and the wall of the compartment defining the chambers are substantially compensated by the compressible means.

3. Fuze as claimed in claim 1, wherein the detonator carrier is pivotally mounted in the compartment so as to pivot from the retracted position to the operative position, the centre of gravity of the detonator carrier being offset relative to the pivot axis of the latter.

4. Fuze as claimed in claim 1, wherein the liquid is silicon.

5. Fuze as claimed in claim 1, wherein the body comprises two elements which have screw-threading and are interconnected by said screw-threading, the compartment being located within the two elements screwed together, a longitudinally extending liquid evacuation passageway being provided in the screwthreading of one of the elements and communicating with the compartment to allow escape of excess amount of said liquid while the elements are being screwed together, outer annular sealing shoulders encompassing the screwthreadings and contained in planes perpendicular to the screwthreadings being provided on the elements in positions to sealingly engage one another and close the evacuation passageway off from the exterior of the body when the elements are fully screwed together.

6. Fuze as claimed in claim 5, comprising two liquid evacuation passageways and two elastically compressible members the volume of which varies with pressure change, the compressible members being mounted in one of said elements and the liquid evacuation passageways putting the two chambers respectively in communication with the compressible members.

7. Fuze as claimed in claim 1, wherein the detonator carrier is mounted in the compartment to pivot about a pivot axis from the retracted to the operative position and comprises two interconnected elements having different densities, the denser element being remote from said pivot axis of the carrier and the less dense element being adjacent said pivot axis.

8. Fuze as claimed in claim 7, wherein the denser element is of metal and the less dense element is of plastic material.

-9. Fuze for a gyratory projectile having a bursting charge, said fuze having a longitudinal axis adapted to coincide with the axis of gyration of the projectile and comprising a body and within the body: a pyrotechnic chain for igniting the bursting change of the projectile and including a primer, a wall defining a fluidtight cornpartment wtihin the body, a primer carrier pivotally mounted in the compartment and carrying the primer and pivotable about a pivot axis substantially parallel with but laterally offset from said longitudinal axis from a retracted position in which the primer of the pyrotechnic chain is out of alignment with the rest of the pyrotechnic chain to an operative position in which the primer is in alignment with the rest of the pyrotechnic chain, the centre of gravity of the carrier being offset relative to the pivot axis of the carrier in such manner that the centrifugal force exerted on the carrier by the gyrations of the projectile urges the carrier to move from the retracted position to the operative position, a part of said wall defining the compaitment being part-cylindrical and concentric with the pivot axis of the carrier, a portion of the carrier being at a very short radial distance from said part-cylindrical part of the wall in all positions of the carrier so as to provide a small-section passageway between said part-cylindrical part and the carrier and the carrier dividing the compartment into two chambers which communicate with each other through said passageway, a viscous motion damping liquid filling the two chambers, whereby the pivoting of the carrier from the retracted position to the operative position is retarded by the action of the liquid which is constrained to flow from one chamber to the other by way of said passageway.

10. Puze as claimed in claim 9, wherein said wall defining the compartment has a second part-cylindrical part concentric with the pivot axis of the carri r and the carrier has a second portion which is at a very short radial distance from said second part of the wall in all positions of the carrier so as to provide a second small section passageway through which the chambers intcrcomrnunicate, said part-cylindrical parts being substantially diametrically opposed relative to the pivot axis of the carrier.

11. Fuze for a gyratory projectile having a longitudinal axis adapted to coincide with the axis of gyration of the projectile and comprising a body and within the body: a pyrotechnic chain for exploding the projectile and including a primer, a wall defining a fiuidtight compartment within the body, a carrier disposed in the compartment and carrying the primer and pivotable in a direction away from said longitudinal axis between a retracted position in which the primer of the pyrotechnic chain is out of alignment with the rest or" the pyrotechnic chain and an operative position in which the primer is in alignment with the rest of the pyrotechnic chain, the centre of gravity of the carrier bein ofiset from said longitudinal axis so that centrifugal force exerted on the carrier by the gyrations, of the projectile urges the detonator carrier away from said retracted position to said operative position, and the carrier dividing the compartment into two chambers, clearances provided between the carrier and said wall defining the compartment and constituting passageways putting the chambers in communication with each other, and a motion damping liquid filling the chambers and the passageways whereby the movement or" the carrier from the retracted position to the operative position is retarded by the action of the liquid which is constrained to flow from one chamber to the other by way of said passageways, said body further comprising a cavity and a striker pin movable in the cavity between a retracted inoperative position and an operative position in which latter position it strikes and thereby ignites the primer when the carrier is in its operative position, a thin perforatable partition wall preventing communication between the cavity and the compartment so that the latter is sealed off in a liquidtight manner from the cavity, the arrangement being such that the striker pin perforates the partition wall in moving from the inoperative position to the operative position of the striker pin.

12. Fuze for gyratory projectile having a longitudinal axis adapted to coincide with the axis of gyration of the projectile and comprising a body and within the body:

pyrotechnic means for e, a ng the projectile, a primer for igniting the pyrotechnic means, a carrier carrying the primer and movable between a retracted position in which the primer is out of alignment with the rest of the pyrotechnic means and an operative position in which the primer is in alignment with the rest of the pyrotechnic means, the carrier being so adapted and arranged that the efiect thereon of the gyration of the projectile is to bias the carrier from the retracted position to the operative position, and means defining a liquid clamping device, said liquid damping device comprising a wall defining a liquidtight compartment, 21 member movable in the compartment from a first position of abutment against a first portion of said wall to a second position of abutment against a second portion of said wall in a direction away from said longitudinal axis, a viscous liquid filling the compartment, and liquid passageways provided between said wall and the member, the member forming two chambers in the compartment which are filled with said liquid and communicate with each other through said passag ways, the positions of said first and second portions of said wall relative to said longitudinal axis being such that said member is held against said first portion of said wall by i ertia when the gyrations of the projectile accelerate whereas when the gyrations continue without acceleration centrifugal force urges said member to said second position thereof, said member being operatively connected to said carrier so as to move the carrier to said operative position when the member moves to said second position.

13. In a fuze for a gyratory projectile having a bursting charge, said fuze having a longitudinal axis adapted to coincide with the axis of gyration of the projectile and being of the type comprising a fuze body and, disposed in the body, a movable percussion pin, a primer for igniting the bursting charge and an arming element which is operatively associated with the percussion pin and is responsive to the centrifugal force created by the gyrations of the projectile so as to be moved by said centrifugal force from a retracted position in which it prevents the percussion pin from striking the primer to an arming position in which it allows the percussion pin to strike the primer, the combination comprising in said fuze body: a wall defining a fluid-tight compartment, said arming element mounted in the compartment and having a pivot axis about which the arming element is pivotable from said retracted position to said arming position, said pivot axis being laterally offset from and substantially parallel with said longitudinal axis, a first abutment and a second abutment provided in the compartment in such positions that the arming element is in abutting relation to the first abutment in said retracted position and in abutting relation to the second abument in said arming position, spring means engaging the arming element for biasing the arming element against the first abutment, the arming element having a centre of gravity which is olfset from said pivot axis and so located relative to said pivot axis and said longitudinal axis that when the projectile gyrates in an accelerating manner the arming element is biased against the first abutment by the effect of inertia whereas when the gyrations cease to accelerate the effect of the centrifugal force created by said gyrations urges the arming element to pivot to said second abutment in opposition to the action of the spring means, the volume of the compartment being greater than the volume of the arming element so as to form a space between the arming element and compartment, a motion damping liquid filling said space and said space being substantially divided into two chambers by the arming element, a clearance being proided between the arming element and said wall for putting the two chambers in communication with each other during the movement of the arming element from the retracted position to the operative position whereby the movement of the arming element to said arming position is retarded by the viscous resistance of the liquid.

14. In a fuze for a gyratory projectile having a bursting charge, said fuze having a longitudinal axis adapted to coincide with the axis of gyration of the projectile and being of the type comprising a fuze body and, disposed in the body, a movable percussion pin, a primer for igniting the bursting charge and an arming element which is operatively associated wtih the percussion pin and is responsive to the centrifugal force created by the gymtions of the projectile so as to be moved by said centrifugal force from a retracted position in which it prevents the percussion pin from striking the primer to an arming position in which it allows the percusson pin to strike the primer, the combination comprising in said fuze body a wall defining a fluid-tight compartment, said arming element mounted in the compartment and having a pivot axis about which the arming element is pivoted from said retracted position to said arming position, said pivot axis being laterally offset from and substantally parallel with said longitudinal axis, a first abutment and a second abutment provided in the compartment in such positions that the arming element is in abutting relation to the first abutment in said retracted position and in abutting relation to the second abutment in said arming position, spring means engaging the arming element for biasing the arming element against the first abutment, the arming element having a centre of gravity which is offset from said pivot axis and so located relative to said pivot axis and said longitudinal axis that when the projectile gyrates in an accelerating manner the arming element is biased against the first abutment by the effect of inertia whereas when the gyrations cease to accelerate the effect of the centrifugal force created by said gyrations urges the arming element to pivot to said second abutment in opposition to the action of the spring means, the volume of the compartment being greater than the volume of the arming element so as to form a space between the arming element and compartment, a motion damping liquid filling said space and said space being substantially divided into two chambers by the arming element, a clearance being provided between the arming element and said wall for putting the two chambers in communication with each other during the movement of the arming element from the retracted position to the operative position, whereby the movement of the arming element to said arming position is retarded by the viscous resistance of the liquid, and elastically compressible means located wtihin said compartment and exposed to said liquid for precluding excessive overpressures of the liquid due to the difference in the expansion of the liquid and that of said wall and arming element.

References Cited in the file of this patent UNITED STATES PATENTS 1,142,375 Smith June 8, 19:15 2,167,197 Brandt July 25, 1939 2,825,284 Kuhn Mar. 4, 1958 2,896,540 Voland July 28, 1959 

1. FUZE FOR A GYRATORY PROJECTILE HAVING A BURSTING CHARGE, SAID FUZE COMPRISING A BODY AND WITHIN THE BODY: A PYROTECHNIC CHAIN FOR IGNITING THE BURSTING CHARGE OF THE PROJECTILE AND INCLUDING A DETONATOR PRIMER, A WALL DEFINING A FLUIDTIGHT COMPARTMENT WITHIN THE BODY, A DETONATOR CARRIER DISPOSED IN THE COMPARTMENT AND CARRYING THE DETONATOR PRIMER AND MOVABLE IN THE COMPARTMENT BETWEEN AN OPERATIVE POSITION IN WHICH THE DETONATOR PRIMER OF THE PYROTECHNIC CHAIN COMMUNICATES WITH SO AS TO BE CAPABLE OF IGNITING THE REST OF THE PYROTECHNIC CHAIN AND A RETRACTED POSITION IN WHICH THE DETONATOR PRIMER DOES NOT COMMUNICATE WITH THE REST OF THE PYROTECHNIC CHAIN, YIELDABLE RETAINING MEANS IN ENGAGEMENT WITH THE DETONATOR CARRIER TO YIELDINGLY RETAIN THE DETONATOR CARRIER IN SAID RETRACTED POSITION WHEN THE PROJECTILE IS NOT GYRATING, THE DETONATOR CARRIER AND RETAINING MEANS BEING SO ADAPTED AND ARRANGED THAT THE EFFECT THEREON OF THE GYRATION OF THE PROJECTILE IS TO MOVE THE DETONATOR CARRIER FROM SAID RETRACTED POSITION IN OPPOSITION TO THE ACTION OF THE RETAINING MEANS TO SAID OPERATIVE POSITION, AND THE DETONATOR CARRIER DIVIDING THE COMPARTMENT INTO TWO CHAMBERS, SMALL-SECTION PASSAGEWAYS PROVIDED BETWEEN THE DETONATOR CARRIER AND SAID WALL DEFINING THE COMPARTMENT AND PUTTING THE CHAMBERS IN COMMUNICATION WITH EACH OTHER, AND A MOTION DAMPING LIQUID FILLING THE CHAMBERS AND PASSAGEWAYS WHEREBY THE MOVEMENT OF THE DETONATOR CARRIER FROM THE RETRACTED POSITION TO THE OPERATIVE POSITION IS RETARDED BY THE ACTION OF THE LIQUID WHICH IS CONSTRAINED TO FLOW FROM ONE CHAMBER TO THE OTHER BY WAY OF SAID PASSAGEWAYS. 